Cationic chlorine-resistant polymeric flocculants and their use

ABSTRACT

Cationic, chlorine-resistant polymeric materials, useful as flocculants, are prepared by reacting an epihalohydrin with a mixture consisting of a lower di-alkylamine and ammonia, where the molar ratio of the amine to ammonia is from about 5:1 to about 2:1, and the ratio of the epihalohydrin to the amine-ammonia mixture is from about 0.9 up to the functional equivalency of the amine mixture, for a time and at temperature conditions such that the resultant polymeric material has a viscosity of about 50 cps to about 4000 cps (Brookfield, spindle 1, 12 rpm) at about 50% real solids content.

BACKGROUND OF THE INVENTION

This is a continuation-in-part application of Ser. No. 393,367 filedAug. 31, 1973, now abandoned.

Surface water clarification systems and certain types of industrialwastewater systems have, in the past, employed inorganic coagulants suchas alum and iron salts. These coagulants have some disadvantages,primary of which is the volume of coagulated sludge. Frequently, thecoagulant and the objectionable solids form a gel mass which isponderous in size and difficult to de-water. Recently cationic polymericmaterials have begun to be used as partial or complete replacements forthe inorganic coagulants, with widely varying results. As surface-waterclarifiers, most cationic polymers have the serious disadvantage ofbeing subject to chlorine attack, rendering them ineffective inattracting oppositely-charged waste solids, and eliminating theirutility to chlorinated potable water clarification systems. Also, somepolymers cannot be used effectively with coagulant aids such as clay,lime, iron salts and alum. Occasionally, it will be desirable to usepolymer to initiate the flocculation of the suspended solids, and thento employ minor amounts of the above standard coagulants to increase thesize of the floc and the settling rate.

On June 12, 1973, a patent issued to Panzer, U.S. Pat. No. 3,738,945,disclosing, in part, a process for producing a polyquaternaryflocculant, by reacting an epihalohydrin, a lower di-alkylamine and apoly-functional amine, which could be ammonia. This disclosure, however,limited the reaction to situations wherein the molar amount of thepolyfunctional amine could be no more than 15% of the total aminecontent of the reaction, and the epihalohydrin to amine ratio must be atleast one.

Well before this patent issued, the applicants herein had discovered amethod by which effective polyquaternary flocculants could be obtainedwith the above general reactants, using ammonia as the polyfunctionalamine, where the molar amount of ammonia can range from about 15% toabout 33%, of the total amine content, and where the ratio ofepihalohydrin to the ammonia - lower di-alkylamine mixture can be from0.9 to the functional equivalency of the amine mixture.

In general, flocculants prepared within the latter amounts of reactants,when diluted to between 45% and 55% real solids content, possess aviscosity of between about 50 cps and 4000 cps (Brookfield, spindle 1,12 rpm), and preferably between about 100 cps and 4000 cps.

The flocculants of this invention are considerably effective inclarifying aqueous systems containing undesirable particulate matter,and are compatible with the conventional flocculating agents, such asalum, clay, and iron salts. They are chlorine-resistant sincesubstantially all of the nitrogen atoms in the polymer are quaternized,with the exception of nitrogens at the very end of the polymer chain.Also, for this reason, the higher the viscosity of the product, whichreflects greater chain length, the fewer non-quaternized nitrogens arepresent. The polymer itself is cationic, with one positive charge pernitrogen group, and is in electrical balance with the equal number ofhalogen anions present.

SUMMARY OF THE INVENTION

It is an object of this invention to produce cationic, polyquaternizedpolymeric material, which is substantially resistant to attack by freehalogen atoms in aqueous media.

It is a further object to produce such polymeric material by reacting alower di-alkylamine, ammonia and an epihalohydrin, where the ammonialevel is from about 15% to about 33% of the total molar amount of theammonia-amine combination, and the ratio of the epihalohydrin to saidcombination is at least 0.9.

DETAILED DESCRIPTION OF THE INVENTION

The polymeric material of this invention is obtained by combining amixture of the lower di-alkylamine and ammonia with the epihalohydrin,in such a manner as to control the heat generated by the exothermicreaction. The temperature is preferably kept below about 60° C, and mostpreferably below about 40° C during the process of combination. Theinitial water content should be between about 25% and 50% on a weightbasis. After about 90% of the epihalohydrin has been combined, themixture is heated to about 90° C, and the remainder of the epihalohydrinis then combined in incremental amounts until the desired viscosity isreached. As the desired viscosity is approached, the mixture is thencooled by external means and/or by addition of water to below about 80°C. If necessary, the reaction can then be terminated by adding acid. Theproduct is also stabilized by lowering the pH to 6 or below.

The preferred di-alkylamine is dimethylamine, however, any di-alkylamine with one to three carbons per alkyl group is considered to beuseful. The preferred epihalohydrin is epichlorohydrin, but theinvention is considered to include any halogen entity.

As mentioned above, the amount of ammonia relative to the total molaramount of the ammonia-amine combination is from about 15% to about 33%,and preferably about 17% to about 25%. The epihalohydrin content can beas low as 0.9 of the ammonia-amine content up to the functional limitsof the NH₃ -amine mixture.

The viscosity of the resultant product will be used to approximate chainlengths of the polymer, (the higher the viscosity, the longer the chain,etc.), and the solids contents referred to hereafter include the organicsolids as well as the anion content, hereafter called the real solidscontent.

EXAMPLE 1

To 450 g. (4.0 mole) of 40% aqueous di-methylamine and 60.8 g. (1.0mole) of 29% aqueous ammonia in a 2000 ml. resin kettle equipped withthermometer, stirrer, reflux condenser, and addition funnel, is addeddropwise, over a period of 2 hours at a temperature below 40° C, 412.9g. (4.5 mole) of epichlorohydrin. The solution is heated at 90° C forone hour. A total of 45.9 g. (0.5 mole) of epichlorohydrin is then addedat 90° C in decreasing portions with the solution being heated at 90° Cfor 20 minutes between each addition. Then, the mixture is cooledexternally down to about 80° C. Sulfuric acid (conc.) is then added tolower the pH to 2.5. The product has a viscosity of about 3600 cps(Brookfield, spindle 1, 12 rpm) when diluted to 50% solids.

Following are additional examples of polymeric material preparedaccording to the procedure of Example 1.

    ______________________________________                                                        Total                                                         Ex-   Mole Ratio                                                                              Moles   EPI,  %     Viscosity Brook-                          ample DMA/NH.sub.3                                                                            Amine   moles Solids                                                                              field Sp. 1, 12 rpm                       ______________________________________                                        2     2/1       6.1     5.7   50    1040                                      3     2.3/1     6.7     6.5   50    2200                                      4     2.3/1     6.7     6.4   50    1100                                      5     3/1       8.1     7.7   50    2650                                      6     3.5/1     4.5     4.6   50    3750                                      7     3.5/1     4.5     4.7   50    1975                                      8     3.5/1     4.5     4.7   50     875                                      9     4/1       5.0     5.5   50     825                                      10    4/1       2.5     3.0   50     912                                      11    4/1       5.0     6.0   50    1250                                      12    4/1       5.0     5.4   50    2000                                      13    4/1       5.0     5.4   50    1550                                      14    4/1       5.0     4.9   50     407                                      15    5/1       4.8     4.9   50     540                                      ______________________________________                                    

Upon simple comparison of the present inventive method steps, as clearlydescribed in the disclosure of the invention and the above example, withthe method steps in the above-discussed patent to Panzer et al it shouldreadily occur to the artisan that the use of a caustic addition freereaction mixture, (i.e., the addition of no caustic other than thatwhich might be imparted by the reactants) accounts for the effectivedialkylamine-ammonia-epihalohydrin flocculant made by the presentinventors in contradistinction to the flocculant taught by Panzer et al.For example, Example 2 of Panzer et al teaches the addition of K₂ CO₃ tothe reaction mixture and Example 3 teaches the addition of NaOH thereto.

The polymeric materials made by the process of this invention weretested for their ability to clarify turbid water samples taken fromLower Natchez Valley Authority River water. The river water is measuredfor turbidity using a turbidimeter calibrated in Jackson Turbidity Units(JTU). A lower number indicates greater water clarity. Analysis of thewater samples indicated that the suspended particles contained thereinwere composed of muds, silts, siliceous materials, organic matter, wastelignin, wood chips, vegetation and tannins.

The data which follow indicate clearly that the polymeric material madeby the process of this invention is effective in substantially improvingthe clarity of the waters.

                  Table 1                                                         ______________________________________                                                 Polymer   Residual    Turbidity                                                                             (JTU)                                  Polymer  Conc., ppm                                                                              Chlorine, ppm                                                                             Initial Final                                  ______________________________________                                        Example 1                                                                              1.5       None        61      23                                     Example 1                                                                              1.75      None        61      18                                     Example 1                                                                              1.75      1           61      23                                     Example 2                                                                              6         None        56      40                                     Example 2                                                                              7         None        56      28                                     Example 4                                                                              0.75      None        66      33                                     Example 4                                                                              1         None        66      21                                     Example 4                                                                              1         1           66      29                                     Example 5                                                                              6         None        65      29                                     Example 5                                                                              7         None        65      22                                     Example 6                                                                              7.5       None        65      41                                     Example 6                                                                              8         None        65      29                                     Example 6                                                                              8         1           65      30                                     Example 9                                                                              2.5       None        54      25                                     Example 9                                                                              2.5       1           54      40                                     Example 9                                                                              3.5       None        81      25                                     Example 9                                                                              3.5       1           81      26                                     Example 9                                                                              8         None        65      26                                     Example 9                                                                              8         1           65      26                                     Example 10                                                                             4         None        81      31                                     Example 10                                                                             4         1           81      31                                     Example 15                                                                             1.5       None        61      24                                     Example 15                                                                             1.75      None        61      19                                     Example 15                                                                             1.75      1           61      23                                     ______________________________________                                    

Generally speaking, it has been found that an average sample ofuntreated turbid river water will require about one week to clarifyitself by settling. When treated with the instant polymeric materials,clarification is accomplished in about five minutes, a more thansubstantial decrease in time.

From the chart, it can be seen that the presence of chlorine has noeffect or only a very slight effect on the functioning of the polymer,thus indicating that the polymeric material is substantially resistantto chlorine attack.

In general, it can be said that the polymeric products of this inventionfunction better as clarifiers the higher their viscosities are,regardless of the particular secondary amine used, or the particularepihalohydrin used. Even with product of lower viscosity, significantwater clarification can be achieved simply by increasing the dosagelevel.

Further tests were conducted to determine the compatibility of theproducts of this invention with standard inorganic coaqulant aids; i.e.,the ability of the instant products to work with coagulant aids inclarifying aqueous systems.

                                      TABLE II                                    __________________________________________________________________________                   Coagulant Aid,                                                                          Polymer                                                                             Turbidity                                                                          (JTU)                                     Polymer                                                                             Water Type                                                                             ppm       Conc., ppm                                                                          Initial                                                                            Final                                     __________________________________________________________________________    Example 1                                                                           Sabine River                                                                           SPV Clay (20)                                                                           2.25  65   30                                        Example 1                                                                           Sabine River                                                                           SPV CLAY (20)                                                                           2.5   65   20                                        Example 1                                                                           Sabine River                                                                           SPV Clay (20)                                                                           3.0   65   11                                        Example 1                                                                           Sabine River                                                                           Alum (10) 1.75  65   26                                        Example 1                                                                           Sabine River                                                                           Alum (20) 0.75  65   35                                        Example 7                                                                           Delaware River                                                                         SPV Clay (15)                                                                           3.0   10   5                                         Example 7                                                                           Delaware River                                                                         Coaguloid Clay (5)                                                                      3.0   10   2.4                                       Example 7                                                                           Sabine River                                                                           SPV Clay (20)                                                                           2.25  65   35                                        Example 7                                                                           Sabine River                                                                           SPV Clay (20)                                                                           2.5   65   25                                        Example 7                                                                           Sabine River                                                                           Alum (10) 1.75  65   25                                        __________________________________________________________________________

In all the above examples, significant clarification was achieved at arate observed to be faster than in instances where clarification wasaccomplished using only polymeric material and no coagulant aid.Examples of other coagulant aids which can be beneficially employed withthe instant polymeric materials are alum, iron salts, lime, coagulantclays and other flocculant polymers.

The amount of the polymeric material of this invention used to clarify agiven turbid water will vary according to the amount of clarificationdesired, the type of turbidity, the viscosity of the treating material,etc. Generally, some clarification will occur no matter what the dosagemay be and regardless of the actual polymeric viscosity. The lower theviscosity, the greater the polymeric dosage will have to be to obtain agiven clarification. Obviously then, the dosage to be applied to a givenaqueous system will depend on the particular facts of the case, anddosage is not considered by the applicants to be critical to theirinvention. Whatever amount is effective for a given purpose isconsidered to be embraced by the instant invention.

To demonstrate the difference between the flocculant made according tothe inventive method and the flocculant made by the method taught byPanzer et al, the following comparative tests were conducted"side-by-side" by one of the present inventors.

EXAMPLE 16

Comparative Product A was made according to those teachings of Panzer etal which most closely approximate the present inventive method. To a oneliter reaction kettle equipped with stirrer, thermometer, additionfunnel and condenser was added 225.0 grams (2.0 moles) of 40% aqueousdimethylamine (DMA) and 20.7 grams (0.35 mole) of 29% aqueous ammonia(NH₃) to render a molar ratio of ammonia to total amines of 15%. Tothis, 185.1 grams (2.0 moles) of epichlorohydrin (EPI) were addeddropwise over three (3) hours, with the temperature being maintained at35°-40° C. When the addition of EPI was complete, the solution washeated to and maintained at 90° C for 30 minutes, at which time 6.0grams (.15 mole) of sodium hydroxide were added. Then, EPI was added in1 ml. portions at 90° C. Twenty minutes after each EPI portion wasadded, the viscosity of the solution was determined by flow through apipette. The addition of EPI in 1 ml. portions, as described, wasrepeated until the desired viscosity was obtained. This required 15portions (17.7 grams, 0.19 mole) of EPI. Next, 146.4 grams of water wereadded. The final viscosity (Brookfield LVT model, spindle 2, 12 rpm) was600 cps. at 50.8% total solids, and the pH was 7.25.

Comparative Product B was made according to the present inventive methodtaught in the specification. To a one liter reaction kettle equippedwith stirrer, thermometer, addition funnel and condenser was added 225.0grams (2.0 moles) of 40% aqueous dimethylamine (DMA) and 20.7 grams(0.35 mole) of 29% aqueous ammonia (NH₃) to render a molar ratio ofammonia to total amines of 15%. To this, 185.1 grams (2.0 moles) ofepichlorohydrin (EPI) were added dropwise over 3 hours, with thetemperature being maintained at 35°-40° C. When the addition of EPI wascomplete, the solution was heated to and maintained at 90° C for 30minutes. Then, EPI was added in 1 ml. portions at 90° C. Twenty minutesafter each EPI portion was added, the viscosity of the solution wasdetermined by flow through a pipette. The addition of EPI, in 1 ml.portions, as described, was repeated until the desired viscosity wasobtained. This required 23 portions (27.14 grams, 0.29 mole) of EPI.Next, 154.4 grams of water were added. The final viscosity was 562 cps.at 50.2% total solids, and the pH was 6.88.

Comparative Products A and B were then placed in an oven at 122° F andthe viscosities were determined periodically. The results are reportedin Table A.

                  TABLE A                                                         ______________________________________                                        Viscosities (cps) of Comparative Product A and Comparative                    Product B placed in 122° F oven                                        Day      1       2       3     4     5    6    7                              ______________________________________                                        Product A                                                                              2000    gel                                                          Product B                                                                               925    1250    2050  4500  --   --   gel                            ______________________________________                                    

On the fifth and sixth days the viscosity of Comparative Product B wasnot determined so that gellation could have occurred on either of thesedays.

From the results reported in Table A it should readily occur to theartisan that, not only is Comparative Product B more stable thanComparative Product A, but that Product B is apparently a differentproduct.

We claim:
 1. The process of flocculating undesirable particulate matterfrom an aqueous medium, which comprises, adding to said medium aneffective amount of a quaternary, cationic, polymeric materialconsisting essentially of the reaction product of a caustic additionfree reaction mixture of an epihalohydrin, ammonia and a lowerdialkylamine, wherein said amine has from 1 to 3 carbons per alkylgroup, wherein the amount of the ammonia ranges from about 15% to 33% ofthe total molar amount of the ammonia-amine concentration, wherein theratio of the epihalohydrin to said ammonia-amine concentration is fromabout 0.9 up to the functional limit of said concentration, and whereinsaid polymeric material has a viscosity of from about 50 cps to about4000 cps (Brookfield, spindle 1, 12 rpm) at a real solids content offrom about 45% to about 55%.
 2. The process of claim 1, furthercomprising adding to said aqueous medium an amount of a coagulant aidalong with said polymeric material.
 3. The process of claim 1, whereinsaid ammonia amount is from about 17% to about 25% of said total molaramount of ammonia-amine concentration.
 4. The process of claim 3,wherein said lower di-alkylamine is di-methylamine and saidepihalohydrin is epichlorohydrin.
 5. The process of claim 4, whereinsaid viscosity is from about 100 cps to about 4000 cps and wherein saidreal solids content is about 50%.
 6. The process of claim 5 furthercomprising adding to said aqueous medium an amount of a coagulant aidalong with said polymeric material.